According to Article 72 of the labor law of the people’s Republic of China, employers and employees must participate in social insurance and pay social insurance premiums according to law.
Article 4 of the social insurance law of the people’s Republic of China also stipulates that employers and employees shall pay social insurance premiums according to law.
In other words, even if the employer and the employee sign the letter of commitment to voluntarily give up social security, it does not have any legal effect.